After a three-day hearing at the Royal Courts of Justice, the Court of Appeal had reserved judgement in the case of Simon Hall, convicted in February 2003 of the murder of 79-year-old Joan Albert.

Mr Hall, now aged 33, was convicted solely on the basis of black nylon flock fibres and polyester fibres found in his addresses and vehicles that were claimed by the prosecution expert at trial, Judith Cunnison, to be highly rare and ‘indistinguishable’ from fibres found at the scene of crime and the deceased’s body. Although no source of the fibres were found, they were allegedly shed by garments worn by the assailant during the commission of the crime.

Cunnison’s evidence has now been seriously undermined by more advanced analysis undertaken by defence expert Mr Tiernan Coyle. In particular, comparison of the black nylon flock fibres under a microspectometer reveal differences in their thickness and chemical composition which can be further discriminated utilising a technique known as First Derivative. They may also not be as rare as what Cunnison led the jury to believe at trial as recent research by Mr Coyle and his assistant Josephine Jones found nylon flock fibres in over 80 per cent of garments that were examined at random. In addition, the polyester fibres claimed by Cunnison to be ‘green’ have now been identified as carbon black in colour and of much less evidential value than what was originally posited at Mr Hall’s trial.

Mr Coyle’s evidence was disputed at the appeal hearing by the prosecution’s new expert, Mr Ray Palmer. Although Palmer concurred at cross-examination that the methods of fibre analysis applied by Coyle are scientifically valid and conceded that there are now proven differences in the fibres originally claimed to be indistinguishable, he maintained that these differences can sometimes also be seen in fibres that originate from the same source garment.

Mr Hall, whose case was investigated by the University of Bristol Innocence Project (UoBIP), is the first case worked on by an innocence project in the UK to be referred back to the Court of Appeal by the Criminal Cases Review Commission. Founded and directed by Dr Michael Naughton, the UoBIP is a pro bono initiative, which involves students working on real cases of prisoners maintaining innocence who have exhausted the normal appeals process and the legal aid system. It is also the first innocence project to be established in the UK and has spawned the creation of innocence projects in over 30 universities in the UK in the last five years.

Questions about the reliability of the fibre evidence in Mr Hall’s case were first publicly raised by Gabe Tan, now research assistant in the School of Law and Assistant Director of the UoBIP in the last ever BBC Rough Justice documentary. In the programme, which was aired back in April 2007, Tan argued that the fact that the fibres are ‘indistinguishable’ is not the same as saying that they are ‘identical’. It merely meant that the fibres cannot be differentiated using the specific technique that was applied by the Forensic Science Service at the time of the investigation.

Arguing for the quashing of Mr Hall’s conviction, Ms Tan stated: “Mr Palmer’s argument is unsustainable. Whilst he may have valid grounds in arguing that the subtle differences in the fibres do not rule out the possibility that they originate from the same garment, equally, these differences substantiate the possibility that they do not. There is no scientific basis for preferring one possibility over another. Fundamentally, the jury were misled into believing that the fibres were highly rare and indistinguishable. This has now been proven to be entirely incorrect. The credibility of the only evidence that led to Mr Hall’s conviction is now seriously undermined and his conviction cannot stand.”

Fibre evidence is regularly used by police forces in the UK and globally to assist in crime scene investigations. However, as fibres, unlike DNA or fingerprints, cannot provide a positive identification of a suspect, they are rarely used to obtain convictions in the absence of other evidence.

Questioning the way in which fibre evidence was used in Mr Hall’s case, Dr Michael Naughton stated: "The future use of fibre evidence in criminal trials rests on the judgment of Simon Hall’s appeal. It is of vital importance to the avoidance of convicting the innocent that the conviction is quashed and it is firmly established that it is inappropriate to use fibre evidence alone in light of its inherent shortcomings."